diff --git a/ethcore/src/block.rs b/ethcore/src/block.rs
index 924d83f8ea4..2a78ec686c8 100644
--- a/ethcore/src/block.rs
+++ b/ethcore/src/block.rs
@@ -370,14 +370,14 @@ impl<'x> OpenBlock<'x> {
 		let mut s = self;
 
 		s.engine.on_close_block(&mut s.block);
-		if s.block.base.header.transactions_root().is_zero() || s.block.base.header.transactions_root().clone() == SHA3_NULL_RLP {
+		if s.block.base.header.transactions_root().is_zero() || s.block.base.header.transactions_root() == &SHA3_NULL_RLP {
 			s.block.base.header.set_transactions_root(ordered_trie_root(s.block.base.transactions.iter().map(|e| e.rlp_bytes().to_vec()).collect()));
 		}
 		let uncle_bytes = s.block.base.uncles.iter().fold(RlpStream::new_list(s.block.base.uncles.len()), |mut s, u| {s.append_raw(&u.rlp(Seal::With), 1); s} ).out();
 		if s.block.base.header.uncles_hash().is_zero() {
 			s.block.base.header.set_uncles_hash(uncle_bytes.sha3());
 		}
-		if s.block.base.header.receipts_root().is_zero() || s.block.base.header.receipts_root().clone() == SHA3_NULL_RLP {
+		if s.block.base.header.receipts_root().is_zero() || s.block.base.header.receipts_root() == &SHA3_NULL_RLP {
 			s.block.base.header.set_receipts_root(ordered_trie_root(s.block.receipts.iter().map(|r| r.rlp_bytes().to_vec()).collect()));
 		}
 		s.block.base.header.set_state_root(s.block.state.root().clone());
diff --git a/ethcore/src/engines/basic_authority.rs b/ethcore/src/engines/basic_authority.rs
index 644eca4546f..332d947c367 100644
--- a/ethcore/src/engines/basic_authority.rs
+++ b/ethcore/src/engines/basic_authority.rs
@@ -153,7 +153,7 @@ impl Engine for BasicAuthority {
 		let gas_limit_divisor = self.our_params.gas_limit_bound_divisor;
 		let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
 		let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
-		if header.gas_limit().clone() <= min_gas || header.gas_limit().clone() >= max_gas {
+		if header.gas_limit() <= &min_gas || header.gas_limit() >= &max_gas {
 			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit().clone() })));
 		}
 		Ok(())
diff --git a/ethcore/src/ethereum/ethash.rs b/ethcore/src/ethereum/ethash.rs
index a1cf05fad65..99c76291dc6 100644
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@@ -131,8 +131,8 @@ impl Engine for Ethash {
 		};
 		header.set_difficulty(difficulty);
 		header.set_gas_limit(gas_limit);
-		if header.number().clone() >= self.ethash_params.dao_hardfork_transition &&
-			header.number().clone() <= self.ethash_params.dao_hardfork_transition + 9 {
+		if header.number() >= self.ethash_params.dao_hardfork_transition &&
+			header.number() <= self.ethash_params.dao_hardfork_transition + 9 {
 			header.set_extra_data(b"dao-hard-fork"[..].to_owned());
 		}
 		header.note_dirty();
@@ -183,7 +183,7 @@ impl Engine for Ethash {
 
 		// TODO: consider removing these lines.
 		let min_difficulty = self.ethash_params.minimum_difficulty;
-		if header.difficulty().clone() < min_difficulty {
+		if header.difficulty() < &min_difficulty {
 			return Err(From::from(BlockError::DifficultyOutOfBounds(OutOfBounds { min: Some(min_difficulty), max: None, found: header.difficulty().clone() })))
 		}
 
@@ -192,7 +192,7 @@ impl Engine for Ethash {
 			header.nonce().low_u64(),
 			&Ethash::to_ethash(header.mix_hash())
 		)));
-		if difficulty < header.difficulty().clone() {
+		if &difficulty < header.difficulty() {
 			return Err(From::from(BlockError::InvalidProofOfWork(OutOfBounds { min: Some(header.difficulty().clone()), max: None, found: difficulty })));
 		}
 
@@ -202,7 +202,7 @@ impl Engine for Ethash {
 			return Err(From::from(BlockError::ExtraDataOutOfBounds(OutOfBounds { min: None, max: None, found: 0 })));
 		}
 
-		if header.gas_limit().clone() > 0x7fffffffffffffffu64.into() {
+		if header.gas_limit() > &0x7fffffffffffffffu64.into() {
 			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: None, max: Some(0x7fffffffffffffffu64.into()), found: header.gas_limit().clone() })));
 		}
 
@@ -218,10 +218,10 @@ impl Engine for Ethash {
 		let result = self.pow.compute_light(header.number() as u64, &Ethash::to_ethash(header.bare_hash()), header.nonce().low_u64());
 		let mix = Ethash::from_ethash(result.mix_hash);
 		let difficulty = Ethash::boundary_to_difficulty(&Ethash::from_ethash(result.value));
-		if mix != header.mix_hash().clone() {
+		if mix != header.mix_hash() {
 			return Err(From::from(BlockError::MismatchedH256SealElement(Mismatch { expected: mix, found: header.mix_hash() })));
 		}
-		if difficulty < header.difficulty().clone() {
+		if &difficulty < header.difficulty() {
 			return Err(From::from(BlockError::InvalidProofOfWork(OutOfBounds { min: Some(header.difficulty().clone()), max: None, found: difficulty })));
 		}
 		Ok(())
@@ -235,13 +235,13 @@ impl Engine for Ethash {
 
 		// Check difficulty is correct given the two timestamps.
 		let expected_difficulty = self.calculate_difficulty(header, parent);
-		if header.difficulty().clone() != expected_difficulty {
+		if header.difficulty() != &expected_difficulty {
 			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: expected_difficulty, found: header.difficulty().clone() })))
 		}
 		let gas_limit_divisor = self.ethash_params.gas_limit_bound_divisor;
 		let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
 		let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
-		if header.gas_limit().clone() <= min_gas || header.gas_limit().clone() >= max_gas {
+		if header.gas_limit() <= &min_gas || header.gas_limit() >= &max_gas {
 			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit().clone() })));
 		}
 		Ok(())